“You have to tend to this garden of democracy, otherwise things can fall apart fairly quickly. And we’ve seen societies where that happens,” Obama said at the Economic Club of Chicago on Tuesday, according to video of the event.

“Now, presume there was a ballroom here in Vienna in the late 1920s or ’30s that looked and seemed as if it, filled with the music and art and literature that was emerging, would continue into perpetuity. And then 60 million people died. An entire world was plunged into chaos,” Obama said. “So you got to pay attention — and vote.”

During the event, the former President mentioned similar themes of responding to a changing political landscape, mentioning examples from America’s history.

“FDR is one of my political heroes. In my mind, the second greatest president after Lincoln. … But he interned a bunch of loyal Japanese Americans during World War II. That was a threat to our institutions,” he said. “There have been periods in our history where censorship was considered OK. We had the McCarthy era. We had a President who had to resign prior to impeachment because he was undermining rule of law. At every juncture, we’ve had to wrestle with big problems.”

Obama also defended the necessity of a free press.

“During my presidency, the press often drove me nuts,” he said. “There were times where I thought reporters were ill-informed. There were times where they didn’t actually get the story right. But what I understood was that principle of the free press was vital, and that, as President, part of my job was to make sure that that was maintained.”

Obama over the past year has occasionally voiced thinly veiled criticisms of the Trump administration’s policies, particularly on climate change, though it’s not clear from the video that he was directly addressing his successor.